Modern data storage devices such as disc drives are commonly used in a multitude of computer environments to store large amounts of data in a form that is readily available to a user. Generally, a disc drive has a data storage disc, or two or more stacked data storage discs, that are rotated by a motor at high speeds. Each disc has a data storage surface divided into a series of generally concentric data tracks where data is stored, such as in the form of magnetic flux transitions.
A data transfer member, such as a magnetic transducer, is moved by an actuator to selected positions adjacent the data storage surface to sense the magnetic flux transitions in reading data from the disc, and to transmit electrical signals to induce the magnetic flux transitions in writing data to the disc. The active elements of the data transfer member are supported by suspension structures extending from the actuator. The active elements are maintained a small distance away from the data storage surface as the data transfer member flies upon an air bearing generated by airflow caused by the spinning discs.
A continuing trend in the industry is toward ever-increasing the data storage capacity and processing speed while maintaining or reducing the physical size of the disc drive. Consequently, continual efforts are being made to miniaturize the data transfer member and supporting structures, increase storage densities, increase disc speed, and decrease fly height. These efforts result in an overall increased sensitivity to vibration.
One source of vibration stems from airflow excitation that is generated by the spinning data storage discs. Airflow currents spiral outwardly in response to the disc rotation, that is, from rotational friction forces and centrifugal forces. If the airflow becomes turbulent it can impart adverse vibrations on the disc and the actuator assembly, likely resulting in actuator positioning errors and data reading and writing errors.
There have been numerous attempts to limit the adverse effects of airflow excitation on the data storage device components. For example, shrouding the peripheral edge of the spinning disc is a well-known and widely practiced solution that effectively reduces the airflow turbidity, especially at the disc edge where turbulence can produce disc flutter. Also, flow straightener members laterally adjacent the data storage surface are commonly employed to minimize the airspace adjacent the outer disc in a disc stack, thereby reducing eddy currents that form in the airflow. Such flow straightening members can be defined by extending boss portions from the enclosure so as to position an airflow conditioning surface portion of the boss in a substantially parallel and close-fitting relationship with the data storage surface.
It can be necessary to provide a clearance niche, or recessed area, in the airflow conditioning surface for movement of the actuator assembly within an operable range of movement. This interruption of the airflow-conditioning surface creates strictly periodical pressure changes and can induce turbulent conditions at and near the actuator. It has been determined that airflow excitation can be reduced by defining a stepped enclosure comprising one or more additional countering niches in the airflow conditioning surface apart from the clearance niche. The size and placement of the countering niche(s) can be selected to compensate for the periodic motion of the disc relative to the clearance niche, thereby suppressing harmonic frequencies of vibration near known resonant frequencies of the disc drive. It is to these improvements and others as exemplified by the description and appended claims that embodiments of the present invention are directed.